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PubMed2005

Linkage disequilibrium analysis of case-control data: an application to generalized aggressive periodontitis.

Several studies have shown a role for the involvement of interleukin (IL)-1 gene cluster polymorphisms in the risk of periodontal diseases. In the present study, we tested polymorphisms, derived from genes of the IL-1 cluster, for association with generalized aggressive periodontitis (GAP) through both allelic association and by constructing a linkage disequilibrium (LD) map of the 2q13-14 disease candidate region. The IL-1RN (VNTR) genotype distribution observed was significantly different in GAP and control subjects (P=0.019). We also observed some evidence for an association between GAP and the IL-1B(+3953) polymorphism (P=0.039). The pattern of association in the region, represented as an LD map, identifies a recombination hot area between the IL-1B(+3953) and IL-1B(-511) polymorphisms. Multilocus modelling of association with disease gives a location for the peak association at the IL-1B(+3953) marker, although support for the peak is not significant. Haplotype analysis identifies a IL-1B(+3953)-IL-1B(-511) haplotype as having the lowest P-value in the region. Recognition of the presence of a recombination hot area between the IL-1B(+3953) and IL-1B(-511) polymorphisms will have an important bearing on future efforts to develop higher resolution SNP analysis in this region for both this and other diseases for which this cluster is implicated.

Case-Control Studies↗
PubMed2006

Single-nucleotide polymorphisms in base excision repair, nucleotide excision repair, and double strand break genes as markers for response to radiotherapy in patients with Stage I to II head-and-neck cancer.

PURPOSE: Polymorphisms in DNA repair genes can influence response to radiotherapy. We analyzed single-nucleotide polymorphisms (SNP) in nine DNA repair genes in 108 patients with head-and-neck cancer (HNSCC) who had received radiotherapy only. METHODS AND MATERIALS: From May 1993 to December 2004, patients with Stage I and II histopathologically confirmed HNSCC underwent radiotherapy. DNA was obtained from paraffin-embedded tissue, and SNP analysis was performed using a real-time polymerase chain reaction allelic discrimination TaqMan assay with minor modifications. RESULTS: Patients were 101 men (93.5%) and 7 (6.5%) women, with a median age of 64 years (range, 40 to 89 years). Of the patients, 76 (70.4%) patients were Stage I and 32 (29.6%) were Stage II. The XPF/ERCC1 SNP at codon 259 and XPG/ERCC5 at codon 46 emerged as significant predictors of progression (p = 0.00005 and 0.049, respectively) and survival (p = 0.0089 and 0.0066, respectively). Similarly, when variant alleles of XPF/ERCC1, XPG/ERCC5 and XPA were examined in combination, a greater number of variant alleles was associated with shorter time to progression (p = 0.0003) and survival (p = 0.0002). CONCLUSIONS: Genetic polymorphisms in XPF/ERCC1, XPG/ERCC5, and XPA may significantly influence response to radiotherapy; large studies are warranted to confirm their role in HNSCC.

Adult↗
PubMed2004

Assessment of DHPLC usefulness in the genotyping of GSTP1 exon 5 SNP: comparison to the PCR-RFLP method.

Single-nucleotide polymorphism (SNP) analysis can be performed by several methods such as PCR-RFLP, real time PCR and mass spectrometry. Denaturating High Pressure Liquid Chromatography (DHPLC) analysis allows the detection of DNA mutations in heteroduplex samples. GSTP1 exon 5 gene presents a single-nucleotide polymorphism (a to g) that results into an amino-acid substitution (Ile to Val). Ile and Val variants are identified respectively by a and b alleles. This polymorphism affects enzyme activity and is highly frequent within Caucasian populations and therefore widely studied in the context of SNP related to cancer susceptibility. Our goal was to evaluate DHPLC usefulness in detecting a well-known SNP in comparison to PCR-RFLP, in the field of molecular epidemiological studies. Fifty Caucasian people were genotyped by both methods. Heterozygous samples were identified easily at two temperatures using the DHPLC method. Discrimination between a/a and b/b homozygous genotypes was done by pooling every homozygous sample with a known a/a sample. Our genotyping using both methods resulted in the characterisation of 32 (64%) a/a homozygous, 18 (36%) a/b heterozygous and 5 (10%) b/b homozygous. All samples were also identically genotyped by the two methods. Our results show that DHPLC is a good alternative to classical PCR-RFLP method in genotyping SNPs. Advantages of this chromatographic method were no restriction site needed and a reduced technical time thanks to an automated injection. Moreover, unlike classical RFLP gel analysis, DHPLC chromatograms provided objective criteria for sample classification.

Acyltransferases↗
PubMed2001

Cambridge Healthtech Institute's Third Annual Conference on Lab-on-a-Chip and Microarrays. 22-24 January 2001, Zurich, Switzerland.

Cambridge Healthtech Institute's Third Annual Conference on Lab-on-a-Chip and Microarray technology covered the latest advances in this technology and applications in life sciences. Highlights of the meetings are reported briefly with emphasis on applications in genomics, drug discovery and molecular diagnostics. There was an emphasis on microfluidics because of the wide applications in laboratory and drug discovery. The lab-on-a-chip provides the facilities of a complete laboratory in a hand-held miniature device. Several microarray systems have been used for hybridisation and detection techniques. Oligonucleotide scanning arrays provide a versatile tool for the analysis of nucleic acid interactions and provide a platform for improving the array-based methods for investigation of antisense therapeutics. A method for analysing combinatorial DNA arrays using oligonucleotide-modified gold nanoparticle probes and a conventional scanner has considerable potential in molecular diagnostics. Various applications of microarray technology for high-throughput screening in drug discovery and single nucleotide polymorphisms (SNP) analysis were discussed. Protein chips have important applications in proteomics. With the considerable amount of data generated by the different technologies using microarrays, it is obvious that the reading of the information and its interpretation and management through the use of bioinformatics is essential. Various techniques for data analysis were presented. Biochip and microarray technology has an essential role to play in the evolving trends in healthcare, which integrate diagnosis with prevention/treatment and emphasise personalised medicines.

Computational Biology↗
PubMed2001

[A model for clinical study based on genome science--trials in disorders of the immune system and allergies].

Disorders of the immune system, such as allergies, have multi-factorial etiologies that include both genetic and environmental components. The recent advances in genome science have facilitated two strategies for studying the genetic basis of disease: (1) systematic analysis of gene expression profiles and (2) comprehensive analysis of gene variations, such as polymorphisms. Here, we describe a unique research institute, Genox Research Inc., that can relate the clinical profile of a patient to genotyping and molecular profiling. Systematic gene expression analyses using differential display have been performed to explore genes related to allergy, and revealed 93 differentially expressed candidate genes in T-cells. Also, a single nucleotide polymorphism(SNP) analysis project has been designed to mine disease-related and/or drug-response-related genes involved in allergic disorders using biochip technologies. As exemplified above, clinical studies based on these applications of genome science would be of considerable value in clarifying our understanding of multi-gene disorders.

Gene Expression Profiling↗
PubMed2006

Genetic control of conventional labeling through the bovine meat production chain by single nucleotide polymorphisms using real-time PCR.

Since January 2002, the European Union has adopted precise guidelines aimed at protecting the safety of meat and controlling the production chain. To this purpose, the conventional traceability of livestock and meat represents the main tool, but verification of traceability requires genetic support. At present, single nucleotide polymorphisms (SNPs) represent the most innovative molecular markers in genotyping studies. The aim of this study was to verify correct labeling in a bovine meat production chain by a real-time PCR protocol based on SNP analysis. Reference hair samples from 5,000 animals were randomly collected from 22 farms. Twelve hundred meat samples were collected at different steps of the bovine meat production chain. In particular, 1,000 meat samples were collected at the slaughterhouse and 200 samples from the same animals directly at the butcher's shop. The protocol was optimized and validated by testing a set of 16 SNP markers on 95 DNA samples from bovine sires of different breeds. Thereafter, the genotyping of 2,200 samples was conducted with a set of 12 selected SNPs to verify traceability of the meat production chain at three different stages: farm, slaughterhouse, and butcher's shop. Irregularities in conventional traceability were evidenced directly in 1.87% of the samples at the slaughterhouse. This percentage increased to 3.25% when sampling was conducted at the butcher's shop. This study demonstrates that despite the precautions adopted over the meat production chain, some critical points still exist that cause the loss of a correct association between registration numbers and samples.

Animal Identification Systems↗
PubMed2006

[Analysis of an AZFc deletion family with natural transmission].

OBJECTIVE: To report a rare family of AZFc deletion with natural transmission and explore the potential mechanism by which identical microdeletions cause different phenotypes. METHODS: Chromosomal quantity and construction were detected by G-band, Y-chromosomal microdeletions by multiple PCR amplification for 12 sequence tagged sites (STSs, and the single-nucleotide polymorphisms (SNPs) of the DAZL gene, the autosomal homologue of deleted-in-azoospermia (DAZ) gene by DNA sequencing. RESULTS: Chromosome analysis revealed a normal karyotype 46, XY in the father and both of his two sons and microdeletions of the full AZFc region were identical, including sY152, sY157, sY242, sY254, sY255, sY239 locus. However, the phenotypes of the affected patients were different: the father had normal fertility, but the sperm density of his two sons deteriorated age-dependently, and the younger one suffered from left cryptorchidism. SNP analysis demonstrated that two polymorphisms in exon 2 and 3 of the DAZL gene were identical in both the father and his sons. CONCLUSION: Identical Y-chromosomal microdeletions causing different phenotypes in this family is not associated with the polymorphisms of DAZL gene and may be related to other genes or environmental factors.

Adult↗
PubMed2005

High-throughput multiplex single-nucleotide polymorphism analysis for red cell and platelet antigen genotypes.

BACKGROUND: Transfusion recipients who become alloimmunized to red cell or platelet (PLT) antigens require antigen-negative blood to limit adverse transfusion reactions. Blood collection facilities use regulated and unregulated antibodies to phenotype blood, the cost of which can be prohibitive depending on the antisera and demand. An alternative strategy is to screen blood for these antigens with genomic DNA and the associated single-nucleotide polymorphisms (SNPs). STUDY DESIGN AND METHODS: A multiplex polymerase chain reaction (PCR)-oligonucleotide extension assay was developed with genomic DNA and a SNP genotyping platform (GenomeLab SNPstream, Beckman Coulter) to identify SNPs related to D, C/c, E, S/s, K/k, Kp(a/b), Fy(a/b), FY0 (-33 promoter silencing polymorphism), Jk(a/b), Di(a/b), and human PLT antigen (HPA)-1a/1b. A total of 372 samples were analyzed for 12 SNPs. The genotypes were compared to the blood group and PLT antigen phenotypes. RESULTS: Individual sample results varied from 98 to 100 percent for 11 of 12 SNPs. D was correctly identified in 292 of 296 (98.6%) D+ donors. The RHCE exon 5 E/e SNP analysis had the lowest concordance (89.5%). Thirty-three R(1)R(1) and 1 r"r were correctly identified. PCR-restriction fragment length polymorphism (RFLP) on selected samples confirmed the presence of the FY0 silencing polymorphism in nine donors. Homozygous HPA-1b/1b was identified in four donors, which was confirmed by PCR-RFLP (n = 4) and anti-HPA-1a serology (n = 2). The two HPA-1a-negative donors were recruited into the plateletpheresis program. CONCLUSION: The platform has the capacity to genotype thousands of samples per day. The suite of SNPs provides genotype data for all blood donors within 36 hours of the start of testing.

Antigens, Human Platelet↗
PubMed2004

[Isolation of free DNA from archived serum samples suitable for molecular genetic studies].

INTRODUCTION: Collected and archived serum samples could be important sources for genetic studies, once DNA suitable for molecular genetic studies could be obtained from them. METHODS: DNA was isolated from 54 archived sera samples, collected previously from the participants of a Hungarian allergy study, with commercially available isolation kit. The authors have determined the concentration of the isolated DNA (81.88 +/- 52.36 ng/ml) and the size of the isolated fragments was estimated using semiquantitative real-time PCR. Two primers were used producing two different fragment size, for the phospholipase 2A and the actin beta genes, and melting curve analyses was performed as quality control. RESULTS: The concentration of the phospholipase 2A product was 2.9798 +/- 5.4454 microg/microl and the actin beta gene was 0.0015 +/- 0.0011 microg/microl. The melting curve analysis served as a quality control for the determination of the size of PCR products. In the case of the phospholipase 2A all samples produced the 133 bp PCR fragments, except one, while in the case of actin beta gene only six sample showed the expected 178 bp product, all the others samples had smaller fragments. CONCLUSIONS: These results confirm the suitability of the DNA isolated from archived sera samples for further molecular biological studies (SNP analysis, mutation detection) and give an estimate for the product size of the isolated DNA. Sera samples have been collected years ago can be a good source of genetic information on different diseases.

Actins↗
PubMed2006

Origin and mechanisms of formation of fetus-in-fetu: two cases with genotype and methylation analyses.

Fetus-in-fetu (FIF) is a condition in which a host infant has a fetus-like mass(es) within its body. We describe here results of molecular genetic analysis in two cases of FIF. In FIF-1, a male host had two retroperitoneal fetiform masses each with a vertebral column, and in FIF-2, a fetiform mass with vertebral column was present in the cranial cavity of a male host. Genotyping of each case using microsatellite markers showed that the host infant and its fetus(es) inherited one copy each of parental alleles and shared identical genotypes. These findings were confirmed by single nucleotide polymorphism (SNP) analysis using Affymetrix GeneChip Human Mapping 50K Array, and supported a monozygotic twin theory of FIF. Analysis of the methylation status was done in both cases at the differentially methylated region (DMR) within the human IGF2-H19 locus after bisulfite treatment, methylation-specific PCR, and cloning of PCR products. Normally, only the paternal allele is methylated and the maternal allele unmethylated in DMR. However, in FIF-1, 7 (46.7%) of 15 clones from a fetiform mass and 6 (66.7%) of 9 clones from the other mass showed an unmethylated paternal allele, while the methylation status of a host infant and its fetiform mass in FIF-2 was the same in all clones examined with normal patterns. These data suggest that in FIF-1, two isolated blastocysts originated from one zygote, one of the two was implanted into (or included by) the other blastocyst during the process of methylation, and such abnormal implantation may have occurred in FIF-2 after the establishment of methylation. This is the first case of FIF showing different methylation patterns between a host infant and fetiform mass.

Adult↗
PubMed2006

Nanopore Detector based analysis of single-molecule conformational kinetics and binding interactions.

BACKGROUND: A Nanopore Detector provides a means to transduce single molecule events into observable channel current changes. Nanopore-based detection can report directly, or indirectly, on single molecule kinetics. The nanopore-based detector can directly measure molecular characteristics in terms of the blockade properties of individual molecules--this is possible due to the kinetic information that is embedded in the blockade measurements, where the adsorption-desorption history of the molecule to the surrounding channel, and the configurational changes in the molecule itself, imprint on the ionic flow through the channel. This rich source of information offers prospects for DNA sequencing and single nucleotide polymorphism (SNP) analysis. A nanopore-based detector can also measure molecular characteristics indirectly, by using a reporter molecule that binds to certain molecules, with subsequent distinctive blockade by the bound-molecule complex. RESULTS: It is hypothesized that reaction histories of individual molecules can be observed on model DNA/DNA, DNA/Protein, and Protein/Protein systems. Preliminary results are all consistent with this hypothesis. Nanopore detection capabilities are also described for highly discriminatory biosensing, binding strength characterization, and rapid immunological screening. CONCLUSION: In essence, the heart of chemistry is now accessible to a new, single-molecule, observation method that can track both external molecular binding states, and internal conformation states.

Base Sequence↗
PubMed2006

Association of hereditary prostate cancer gene polymorphic variants with sporadic aggressive prostate carcinoma.

BACKGROUND: ELAC2, MSR1, and RNASEL are candidate genes for hereditary prostate carcinoma (HPC). While, studies have demonstrated that single nucleotide polymorphisms (SNPs) in these genes are associated with sporadic disease as well as HPC, these results are often not replicated in follow-up studies. Given that the majority of patients studied had localized disease and up to 50% of localized prostate cancer is clinically insignificant, the inability to replicate the initial findings may reflect that some subjects had indolent tumors. Herein, we examine patients with metastatic disease to determine if an association exists between HPC SNPs and unambiguously significant prostate cancer. METHODS: We examined polymorphisms within ELAC2 (S217L, A541T, E622V), MSR1 (P275A, R293X, aIVS5-59c), and RNASEL (E265X, R462Q, D541E) in 150 European-Americans with metastatic prostate cancer and 170 prostate cancer-free controls using pyrosequencing assays. RESULTS: Only ELAC2 217L (37% cases vs. 29% controls (P=0.034)) and RNASEL 541E (61% cases vs. 53% controls (P=0.045)) were over-represented. Analysis of genotypes revealed that presence of the leucine ELAC2 allele (OR 1.54: 95% CI=0.99-2.41, SS vs. SL, LL) and homozygosity for the glutamic acid RNASEL allele (OR 1.68: 95% CI=1.04-2.70, EE vs. DE, DD) were associated with increased risk. Patients with both genotypes were of particularly high-risk (OR 2.66: 95% CI=1.36-5.19). CONCLUSIONS: These results suggest that, in a European-American population, ELAC2 217L and RNASEL 541E are associated with metastatic sporadic disease. ELAC2 and RNASEL SNP analysis may prove useful in determining which patients are at risk for developing clinically significant prostate carcinoma.

Base Sequence↗
PubMed2026

Difficult-to-treat resistant Gram-negative bacteria and genomic resemblances between colonization and infection among patients in an intensive care unit of a tertiary care hospital in Bangladesh.

Colonization with difficult-to-treat-resistant Gram-negative bacteria (DTR-GNB) increases the risk of subsequent infections with limited treatment options. This study aimed to assess the burden of DTR-GNB colonization in ICU patients, explore its association with clinical outcomes, and examine genomic similarities. This secondary analysis included patients enrolled within 24 h of ICU admission between July 2023 and January 2024. Rectal swabs were collected at enrollment, on days 3, 7, and weekly during ICU stay to detect colonization. Bacterial isolates grown on selective chromogenic agar media were identified and tested for antimicrobial susceptibility using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and automated broth microdilution, respectively. Blood, urine, and/or tracheal aspirate cultures were performed if clinically suspected sepsis. Whole-genome sequencing (WGS) was performed on paired colonization and infection isolates, and genomic relatedness was assessed using FastANI, core-genome single-nucleotide polymorphism (SNP) analysis, and phylogenetic reconstruction. Among 373 patients, 181 (48.5%) were colonized with DTR-GNB; 76 (20.4%) at enrollment, and 105 (53.0%) acquired during hospital stay. Among 52 (13.9%) patients evaluated for suspected infection, 30 (57.7%) had positive cultures, predominantly Acinetobacter baumannii (n = 15) and Klebsiella pneumoniae (n = 11) of DTR-phenotypes. Compared to non-colonized patients, patients colonized with DTR-GNB had higher risks of infections (risk ratio [RR]: 2.18, 95% CI: 1.27-3.76) and longer ICU stays (median 7 vs 2 days, P < 0.001). DTR-GNB-infected patients had a higher risk of death (RR: 1.57, 95% CI: 1.34-1.84) compared to patients without DTR-GNB infection. WGS revealed that 13 of 14 paired colonization-infection isolates were conspecific, with three pairs being highly clonal; whereas the remaining pairs showed greater genomic divergence, consistent with the SNP and phylogenetic analyses. While common, more than half acquired DTR-GNB colonization from the ICU. Its association with subsequent infection and prolonged ICU stays underscores the need for enhanced infection prevention and control measures to mitigate nosocomial transmission and improve patient outcomes.IMPORTANCEThis study underscores the growing threat posed by difficult-to-treat resistant Gram-negative bacteria (DTR-GNB) in intensive care units. Nearly half of critically ill patients were colonized, with a considerable proportion acquiring these multidrug-resistant organisms during their ICU stay. Colonization with these pathogens substantially increased the risk of subsequent infections, even by the same colonizing strain, prolonged ICU stays, and likely worsened clinical outcomes due to the unavailability of susceptible antibiotics. Alarmingly, more than 90% of patients infected with DTR-GNB expired in the hospital. These findings highlight the urgent need for robust infection prevention and control strategies to curb nosocomial transmission and mitigate the impact of DTR-GNB on vulnerable patient populations. Addressing this emerging resistance phenotype is critical to improving patient safety and reducing the burden on healthcare systems.

Humans↗
PubMed2001

Molecular genetic analysis of appendiceal mucinous adenomas in identical twins, including one with pseudomyxoma peritonei.

Pseudomyxoma peritonei (PMP) is a clinical syndrome characterized by mucinous ascites and peritoneal lesions composed of histologically bland to low-grade adenomatous mucinous epithelium within pools of extracellular mucin, often with an associated mucinous adenoma of the appendix. There is evidence that the peritoneal lesions in PMP are clonally derived from the associated appendiceal adenoma. Little is known about the molecular genetic alterations or hereditary factors involved in the development of appendiceal mucinous tumors and PMP. We report the only known example of appendiceal mucinous adenomas in identical twin brothers, one of whom developed PMP. We analyzed the status of the K-RAS and APC genes in these tumors using digital polymerase chain reaction and digital single nucleotide polymorphism (SNP) assay. Identical K-RAS mutations were detected in the appendiceal adenoma and peritoneal tumor from the twin with PMP, whereas the adenoma from the other twin harbored a different mutation. Digital SNP analysis demonstrated loss of heterozygosity of APC only in the adenoma from the twin without PMP but not from the appendiceal or peritoneal tumors of the twin with PMP. The adjacent normal tissue in each case retained both APC alleles. The K-RAS mutational analysis supports the view that PMP is clonally derived from the associated appendiceal mucinous adenoma. The lack of loss of heterozygosity of APC in the adenoma and peritoneal tumor from the twin with PMP suggests that loss of heterozygosity of APC is not necessarily involved in the development of all appendiceal adenomas or PMP. The different types of mutations in K-RAS and the different allelic status of the APC locus in the tumors from both twins suggest that mutation in K-RAS and loss of heterozygosity of APC occurs somatically in adenomas and is independent of the identical genetic background of the twins.

Adult↗
PubMed2005

Genome amplification of single sperm using multiple displacement amplification.

Sperm typing is an effective way to study recombination rate on a fine scale in regions of interest. There are two strategies for the amplification of single meiotic recombinants: repulsion-phase allele-specific PCR and whole genome amplification (WGA). The former can selectively amplify single recombinant molecules from a batch of sperm but is not scalable for high-throughput operation. Currently, primer extension pre-amplification is the only method used in WGA of single sperm, whereas it has limited capacity to produce high-coverage products enough for the analysis of local recombination rate in multiple large regions. Here, we applied for the first time a recently developed WGA method, multiple displacement amplification (MDA), to amplify single sperm DNA, and demonstrated its great potential for producing high-yield and high-coverage products. In a 50 mul reaction, 76 or 93% of loci can be amplified at least 2500- or 250-fold, respectively, from single sperm DNA, and second-round MDA can further offer >200-fold amplification. The MDA products are usable for a variety of genetic applications, including sequencing and microsatellite marker and single nucleotide polymorphism (SNP) analysis. The use of MDA in single sperm amplification may open a new era for studies on local recombination rates.

Genomics↗
PubMed2003

Single-nucleotide polymorphism analysis using fluorescence resonance energy transfer between DNA-labeling fluorophore, fluorescein isothiocyanate, and DNA intercalator, POPO-3, on bacterial magnetic particles.

To develop an analytical system for single-nucleotide polymorphisms (SNPs), the fluorescence resonance energy transfer (FRET) technique was employed on a bacterial magnetic particle (BMP) surface. A combination of fluorescein isothiocyanate (FITC; excitation 490 nm/emission 520 nm) labeled at the 5' end of DNA and an intercalating compound (POPO-3, excitation 534 nm/emission 570 nm) was used to avoid the interference from light scattering caused by nanoparticles. After hybridization between target DNA immobilized onto BMPs and FITC-labeled probes, fluorescence from POPO-3, which was excited by the energy from the FITC, was detected. The major homozygous (ALDH2*1), heterozygous (ALDH2*1/*2), and minor homozygous (ALDH2*2) genotypes in the blood samples were discriminated by this method. The assay described herein allows for a simple and rapid SNP analysis using a fully automated system.

Bacterial Proteins↗
PubMed2003

Dissection of genomewide-scan data in extended families reveals a major locus and oligogenic susceptibility for age-related macular degeneration.

To examine the genetic basis of age-related macular degeneration (ARMD), a degenerative disease of the retinal pigment epithelium and neurosensory retina, we conducted a genomewide scan in 34 extended families (297 individuals, 349 sib pairs) ascertained through index cases with neovascular disease or geographic atrophy. Family and medical history was obtained from index cases and family members. Fundus photographs were taken of all participating family members, and these were graded for severity by use of a quantitative scale. Model-free linkage analysis was performed, and tests of heterogeneity and epistasis were conducted. We have evidence of a major locus on chromosome 15q (GATA50C03 multipoint P=1.98x10-7; empirical P< or =1.0x10-5; single-point P=3.6x10-7). This locus was present as a weak linkage signal in our previous genome scan for ARMD, in the Beaver Dam Eye Study sample (D15S659, multipoint P=.047), but is otherwise novel. In this genome scan, we observed a total of 13 regions on 11 chromosomes (1q31, 2p21, 4p16, 5q34, 9p24, 9q31, 10q26, 12q13, 12q23, 15q21, 16p12, 18p11, and 20q13), with a nominal multipoint significance level of P< or =.01 or LOD > or =1.18. Family-by-family analysis of the data, performed using model-free linkage methods, suggests that there is evidence of heterogeneity in these families. For example, a single family (family 460) individually shows linkage evidence at 8 loci, at the level of P<.0001. We conducted tests for heterogeneity, which suggest that ARMD susceptibility loci on chromosomes 9p24, 10q26, and 15q21 are not present in all families. We tested for mutations in linked families and examined SNPs in two candidate genes, hemicentin-1 and EFEMP1, in subsamples (145 and 189 sib pairs, respectively) of the data. Mutations were not observed in any of the 11 exons of EFEMP1 nor in exon 104 of hemicentin-1. The SNP analysis for hemicentin-1 on 1q31 suggests that variants within or in very close proximity to this gene cause ARMD pathogenesis. In summary, we have evidence for a major ARMD locus on 15q21, which, coupled with numerous other loci segregating in these families, suggests complex oligogenic patterns of inheritance for ARMD.

Aged↗
PubMed2026

Inference of Genetic Structure and the Process of Population Formation in Nepalese Native Goats Using Uniparental and Genome-Wide Markers.

Nepal is a small, landlocked country with marked elevational variation from the Terai plains to the Himalayas. Here, four indigenous goat populations (Chyangra, Sinhal, Khari, and Terai) are raised at different elevations. This study aimed to clarify the genetic structure of these populations and how they are formed and propagated across the Himalayan region. We analyzed 136 Nepalese goats using mitochondrial (mt) DNA D-loop and sex-determining region Y (SRY) 3'-untranslated region (UTR) sequences, as well as 50 K SNP array data. The mtDNA haplogroups D (0.162) and G (0.03) were detected only in Chyangra, whereas haplogroup B was predominant in Sinhal (0.42), followed by Khari (0.260). Regarding SRY haplotypes, Y2B was detected in all populations, whereas Y1AB (0.42) was found only in Chyangra. Genome-wide SNP analysis showed that Chyangra was genetically related to Tibetan and Central Asian goats, while Terai resembled South Asian goats. Interestingly, Sinhal formed a distinct cluster, whereas Khari exhibited an admixed genetic structure. These findings suggest that Nepalese goats originate from at least three ancestral lineages and that an additional migration route may have existed through the southern Himalayas.

50K SNP↗